Semiconductor devices are used in many electronic and other applications. Semiconductor devices comprise integrated circuits that are formed on semiconductor wafers by depositing many types of thin films of material over the semiconductor wafers, and patterning the thin films of material to form the integrated circuits.
There is a demand in semiconductor device technology to integrate many different functions on a single chip, e.g., manufacturing analog and digital circuitry on the same die. In such applications, large capacitors are extensively used for storing an electric charge. They are rather large in size, being several hundred micrometers wide depending on the capacitance, which is much larger than a transistor or memory cell. Consequently, such large capacitors occupy valuable silicon area increasing product cost. Such large capacitors are typically used as decoupling capacitors for microprocessor units (MPU's), RF capacitors in high frequency circuits, and filter and analog capacitors in mixed-signal products.
One of the goals in the fabrication of electronic components is to improve product speed. One way of improving product speed is by reducing interconnect parasitic capacitance. Hence, the semiconductor industry has increasingly adopted low-k materials. However, introduction of low-k materials introduces a number of reliability problems. For example, micro-cracks or nano-indents present on the edge of the chip after dicing can easily propagate through the low-k material layers and result in structural defects, delaminations or collapse. Similarly, moisture from the atmosphere may be absorbed into the active device region through the porous low-k material layers. This moisture can oxidize metallic materials present in the semiconductor chip as well as result in drift of product performance during operation. Hence, additional structures, taking up valuable chip area, are added to the chip to avoid these deleterious effects.
Thus, what are needed in the art are cost effective ways of forming semiconductor chips with increased functionality, good reliability, but without significant utilization of chip area.